Thematic Bible: The real heir born

And the LORD visited Sarah as he had said, and the LORD did to Sarah as he had spoken. For Sarah conceived and bore Abraham a son in his old age, at the set time of which God had spoken to him. And Abraham called the name of his son that was born to him, whom Sarah bore to him, Isaac. read more.
And Abraham circumcised his son Isaac, being eight days old, as God had commanded him. And Abraham was a hundred years old, when his son Isaac was born to him. And Sarah said, God hath made me to laugh, so that all that hear will laugh with me. And she said, Who would have said to Abraham, that Sarah shall nurse children? for I have borne him a son in his old age.